Dual mode disk player/recorder

Abstract

In a compatible recording and reproducing apparatus which is capable of recording and reproducing information on both a video disk and a digital audio disk, a relative angle between an optical axis of a laser beam emitted from a pickup and the disk is adjusted so as to be suitable for the disk loaded on the apparatus. Further, the movement of the pickup in the radial direction of the disk is regulated in accordance with the difference in the outer diameter of the two kinds of disks. A problem due to the difference of the track pitch in the two kinds of disks is solved by moving the pickup in a direction perpendicular to a radial direction of the disk. In addition, an objective lens for focusing the laser beam on the disk is selected within a predetermined range of an effective numerical aperture in order to simplify an optical system of the apparatus.

What is claimed is: 
     
       1. A compatible apparatus for optically recording information on and reproducing information from a first, video disk and a second, audio disk, each of said disks having a plurality of parallel recording tracks said apparatus comprising: recording/reproducing means (2) for recording information on and/or reproducing information from said first and second disks utilizing a laser beam; discriminator means (33) for discriminating between a video disk and an audio disk by sensing at least one parameter selected from the group consisting of disk thickness, disk diameter, disk weight, disk surface optical reflectance, disk spindle hole diameter, and reproduced signal characteristics, angle detection means (9) for detecting a relative angle between an optical axis of light emitted (3) from said recording/reproducing means and a disk loaded into said apparatus; angle adjustment means (32) responsive to an output signal from said angle detection means for driving said recording/reproducing means in a manner to maintain a predetermined angle of said optical axis relative to said loaded disk, and means (34, 35) responsive to an output signal from said discriminator means for setting said predetermined angle at a first value during information recording and reproduction on said first disk and at a second value during information recording and reproduction on said second disk, wherein said first value (θ v ) substantially maximizes an RF signal level and is different from said second value (θ a ) which minimizes jitter. 
     
     
       2. An apparatus according to claim 1 wherein said angle detection means comprises a light emitting element, a pair of light receiving elements, said pair of light receiving elements receiving light emitted from said light emitting element and reflected from said disk, and a differential amplifier having a first input receiving an output of one of said pair of light receiving elements and a second input receiving an output of the other light receiving element. 
     
     
       3. An apparatus according to claim 2 wherein said angle adjustment means comprises gain controlling means connected between said one of the light receiving elements and said first input of said differential amplifier, wherein said gain controlling means operates in response to said first and second output signals outputted from said disk discriminator means. 
     
     
       4. An apparatus according to claim 1 further comprising position detection means for detecting a radial position of said recording/reproducing means with respect to said disk, wherein the relative angle of said optical axis is adjusted in response to a signal from said position detection means only when said recording/reproducing means is within a predetermined portion of the radius of said disk. 
     
     
       5. An apparatus according to claim 4 wherein when the position of said recording/reproducing means has exceeded said predetermined portion of the radius of said disk, the relative angle of said optical axis is maintained at a state immediately before the occurence of exceeding of said recording/reproducing means. 
     
     
       6. An apparatus according to claim 1 further comprising means for generating a tracking error signal, said tracking error signal being generated in response to outputs from a second pair of light receiving elements, and means by which a relative angle formed between a line connecting a pair of beam spots to be received in said second pair of light receiving elements and a line along a recording track is set to a value associated with a track pitch of the recording tracks on said disk. 
     
     
       7. An apparatus according to claim 6 wherein said value is set by changing the position of said recording/reproducing means relative to said disk in a direction substantially perpendicular to the radial direction of said disk. 
     
     
       8. An apparatus according to claim 6 wherein said value is set by rotating said recording/reproducing means about said optical axis. 
     
     
       9. An apparatus according to claim 1 further comprising an objective lens by which the laser beam is focused on said first and second disks has an effective numerical aperture NA/λ of not lower than 0.57 but not higher than 0.68, where NA is a numerical aperture of said objective lens and λ is a wavelength in microns of the laser beam.